Is NetApp certified, with vSphere ESX4.x, the answer is Yes. Firstly it's not realy a question where it's fas or v-sieries, both use Data ONTAP so no problems.
have a look at http://www.vmware.com/netapp for best practice guides on the VMware site or the NetApp technical library
In regards to the funcationalities that your potential customer is looking for:
1.) Growth not the same lun, but you create a new lun and extend the required datastore.
Example Datastore 100g (Lun 100g) increate to Datastore 200g (Lun 100g + Lun 100g) on the fly
2.) Feature from vSphere, provided the disks have be created in a way to allow for expansion.
3.) Best Practice from NetApp for deployment with VMWare, could possibly get the best performance using NFS protocols
4.) Using SnapManager for VI, will provide this.
Hope this helps Good Luck.